This program will provide predoctoral training of students preparing for research careers in Molecular, Cellular, and Systems Neuroscience. It involves 26 faculty members from the Biology, Physics, Chemistry, and Engineering Divisions. It is a continuation of a program previously supported by NIH. Some research areas of special emphasis are: 1) neural development (control of cell fate, axon guidance and synaptogenesis in a variety of systems); 2) signal transduction mechanisms in neurons (sensory processing in the visual and olfactory systems of vertebrates and invertebrates, and synaptic transmission and plasticity in hippocampal neurons); 3) behavior (simple and complex behaviors in vertebrates, arthropods, and nematodes); 4) computational neuroscience (studies of single neurons, system of neurons, and whole organisms). The major components of our training activities are: 1) each student's individual research program under one or more faculty sponsors; 2) an organized curriculum of graduate courses; 3) preparation for qualifying examinations; 4) teaching activities; 5) an extensive and wide-ranging seminar program. Support is requested for 16 predoctoral trainees, who will be admitted to graduate study for a Ph.D. in Biology or in Computation and Neural Systems. Criteria for admission into the program include a strong motivation for a career in research and high quantitative ability. Our expectation that trainees will continue into productive research careers is supported by the records of previous trainees. Caltech has a strong commitment (at both the institutional and the Divisional levels) to increasing the representation of minorities in science. In the Biology program, we have made special efforts to attract exceptionally talented students from under-represented minority groups, and we have been quite successful in this effort in recent years. A number of these students are primarily interested in neuroscience research. The training faculty are located within several building clustered near each other on the Caltech campus. Multi-user facilities include DNA sequencing, oligonucleotide synthesis, peptide synthesis, protein expression and purification, monoclonal antibody production, a transgenic and 'knockout' mouse facility, and the Biological Imaging facility.